Dissertation/Thesis Abstract

Geophysical Investigation of Carrizo Formation by Using Two-Dimensional Seismic Surveys in the Tullos-Urania Oilfield in LaSalle Parish, LA
by Ghalayini, Zachary T., M.S., University of Louisiana at Lafayette, 2018, 77; 13419750
Abstract (Summary)

The upper Wilcox group in the Tullos-Urania oilfield has not been imaged with enough resolution for interpretation. Prior seismic data collected in the area was designed for formations much deeper than the Wilcox Group. The purpose of this investigation was to produce an image of the subsurface and identify formations of interest for production of oil and gas by applying different processing methods. With an optimal processing workflow and use of limited well logs, an interpretation of the data was provided to the oil company.

The advantage of using an accelerated weight-drop source is the shallow horizons, ranging from 1,500 to 3,000 feet in-depth, become distinct with higher resolution. The acquisition achieved a dominant frequency averaging around 45–65 Hz compared to a nearby pre-existing 3D survey volume with a dominant frequency range of 15–35 Hz. Refracted waves dominated the unprocessed shot records from this data. Consequently, the field records had a significantly low signal-noise ratio. Therefore, the most critical processing steps focused on signal processing and velocity analysis. Without enough ground roll and noise suppression, the velocity analysis would not have been coherent. Some obstacles faced with processing the data included a sparse horizontal sampling and a lack of velocity logs along the seismic line.

The results of this study included a set of stacked lines, velocity models, and an optimal processing workflow for future high-frequency shallow seismic exploration surveys in the vicinity of LaSalle, LA. These results have concluded seismic surveying with an accelerated weight-drop source is a cost-effective method to produce a high- resolution cross-section of the high and low-velocity sand and shale channels of the fluvial Wilcox strata of Northern Louisiana. Further research should look to build on these results and gather a 3D survey to image the structure of the Tullos-Urania oilfield and identify hydrocarbons-in-place.

Indexing (document details)
Advisor: Zhang, Rui
Commitee: Gottardi, Raphael, Kinsland, Gary L.
School: University of Louisiana at Lafayette
Department: Geology
School Location: United States -- Louisiana
Source: MAI 58/05M(E), Masters Abstracts International
Subjects: Geology, Geophysics, Geomorphology
Keywords: Carrizo Formation, Geology, Geophysics, Seismic processing, Wilcox Group
Publication Number: 13419750
ISBN: 978-1-392-04220-5
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